The present invention relates to a new and improved construction of guide apparatus for a rigid starting or dummy bar.
Generally speaking, the present invention concerns a continuous casting installation for the casting of strands. This casting installation contains a flow-through continuous casting mold, a secondary cooling zone, a rigid starting or dummy bar which can be introduced through the secondary cooling zone into the continuous casting mold, and a withdrawal and straightening unit or machine containing drive or pinch rolls for driving the cast strand and/or starting bar. Additionally, there is provided a suspension device for the starting bar at a position spaced or remote from the region of the cast strand guides or roller apron, as well as a further or second transport device for the starting bar, by means of which the starting bar, after departing from the withdrawal and straightening unit, can be moved into a rest or ineffectual position.
In German patent publication No. 2,629,453 and the corresponding U.S. Pat. No. 3,930,533 granted Jan. 6, 1976, there has been disclosed to the art a continuous casting machine for casting strands which contains a long rigid starting bar which, during withdrawal by the withdrawal and straightening unit, can be moved into its rest position. The foot or tail-end of such starting or dummy bar is introduced into a free wheeling gear blocking device. With this system the entire movement of the starting bar is accomplished by the same drive or pinch rolls.
What is disadvantageous with this type of starting bar drive is that the starting bar together with the thereat connected cast strand must be conveyed into its rest or ineffectual position. On the one hand, upon reaching such rest position a terminal switch must generate a signal for interrupting the drive which, during this phase, already acts upon the cast strand which displaces the starting bar in front of such cast strand. On the other hand, the head portion or end of the cast strand, at this moment in time, is already at a relatively great distance from the horizontal tangent of the cast strand and there is required a correspondingly great amount of energy for straightening the cast strand, since the starting bar must be withdrawn far enough out of the cast strand guides or roller aprons.
This shortcoming was already eliminated by means of the casting installation disclosed in U.S. Pat. No. 3,344,844, granted Oct. 3, 1967. In that prior art system the starting bar, after departing from the drive or pinch rolls, is pulled by means of a traction cable into its rest position, and the disconnection of the starting bar is accomplished at a site near to the horizontal tangent The drawback of this state-of-the-art construction, as well as also a further drawback of the installation disclosed in the aforementioned German patent publication No. 2,629,453 and the corresponding U.S. Pat. No. 3,930,533 as well as appertaining to further known installations, such as disclosed for instance in the German patent publication No. 2,714,338 and U.S. Pat. No. 3,628,595, granted Dec. 21, 1971, resides in the fact that the diverse guide and drive devices for the starting bar are arranged in an immobile manner above the cast strand guides or roller apron, so that it is difficult or, in fact, impossible to have access to the cast strand guides from above by means of a crane or the like, something of appreciable importance during repair and maintenance work.